Field of the Invention
The present invention relates to a pneumatic tire that offers low rolling resistance while maintaining wet performance.
Description of the Related Art
A pneumatic tire having low rolling resistance is strongly requested for heavy load vehicles such as a truck or bus that consumes large amount of fuel.
It is well known that energy loss of tire rubber greatly contributes rolling resistance of the tire. Therefore, in order to improve rolling resistance of the tire, an improved rubber composition with low energy loss has been proposed. However, the improved rubber composition with low energy loss tends to have some undesirable property with respect to durability, wear resistance, and crack resistance.
In order to improve rolling resistance of the tire, Japanese Unexamined Patent Application Publication No. 2006-341769 discloses an improved tread pattern shown as in FIG. 9. The tread pattern comprises six block rows each of which includes a plurality of tread blocks “c” defined by circumferentially extending main grooves “a” and a plurality of lateral grooves “b”. The central main groove “a” is configures to a zigzag groove “d” in order to offer low rolling resistance while maintaining wet performance.
However, a pneumatic tire having further improved low rolling resistance is requested in recent years.